355 ci sbc with a gt42 turbo
im thinking it would get boost creep with a single 50mm gate
any recomendations

 

How much boost?

 

not sure just yet prolly start around 7-9 psi and slowly work up

 

I will try to measure the diameter of the flapper valve on the internal WG turbine this evening. From memory it is much smaller than 50mm.
I don't see a 50mm WG being a problem at 800 FWHP.

 

ok figured id dbl check though,we have a customer with a ford lightning that has a 302 sbf with a single turbo,the trucks in the 8's and he had to run dual 2 inch gates to avoid boost creep

 

What year? Lightning has had S/C 's for the last few years of production.

Running 8's, seems like lots of boost hence the 50mm not being enough.

But then again, what do I know...








I can teach you how to blow a motor, haha.

 

now this wasnt an originally s/ced lightning, hes in the 8's with i wanna say 18 psi.with a single 2 inch gate the boost crept up over 22psi on the dyno before they shut it down..106mm turbo

 

Oh, was it the pre-96 body? They had a N/A 351 from the factory and could beat a 5.0 Mustang with 30 sheets of 1/2" plywood in the back, lol, saw that in Fast Fords mag when the "box-shaped" lightning came out.

 

I couldn't measure the flapper valve on the internal wastegate directly with a tape measure. It "feels" like the diameter is about 1".

 

after talking with a few ppl. the setup is gonna get 2 50mm wastegates 2 be on the safe side. a single 50mm prolly wont be able to control boost

 

Wastegate size would depend on how big the engine is, how small the exhaust turbine is, and how little boost you run. Bigger engine, smaller turbine, or less boost means you'll need a larger WG to bleed off the pressure to keep the turbo from spooling up too fast. You'd think I'd be the worst case situation, running only 5 psi right now on a 399 with AFR heads, a 6000 redline, and a small .59 A/R turbine section on the two turbos (Garrett T04E's). This is with two tiny Turbonetics Deltagates, which have a 1.25" (just under 32mm) piston, and there's no boost creep.

 

An OEM vehicle GT4294 is usually a diesel flanged unit with an A/R of 1.14 or bigger. The most common seem to be 1.28 or 1.44 A/R. Check out turbobygarrett.com for the turbine maps. You need a flow a lot of air to hit the limit and need to dump the rest to the wastegate. I don't see why a 50mm wouldn't work.